Heating apparatus



//v VISA/Top d; if P 5 Sheets-Sheet l D. W. WILSON' HEATING APPARATUS Original Filed March 14, 1932 June 17, 1941.

Jui-.e 17, 1941. D, W, WlLSON 2,246,027

HEAT ING APPARATUS original Filed March 14,1932 5 sheets-sheer, 2

June 17, 1941. D. w. WlLsoN HEATING APPARATUS 5 Sheets-Sheet 5 Original Filed'March 14, 1952 m5/.22,3% c7 vf f N c ,165, ,fa Hui: \/Q: anx o man June 17, 1941.

D. N. WILSON HEATING APPARATUS 19152 5 Sheets-Sheet 4 Original Filed March 14 June 17, 1941. D. w. WILSON HEATING APPARATUS 5 Sheets-Sheet 5 Original Filed March 14, 1932 A J \\\N .Nov

w Ef @9 M! m9 f ETE@ FTEN'' HEATING APPARATUS Dustin W. Wilson, 'Scarsdala N. Y., assigner to Gasoline Products Company, Inc., Newark, N. J., a corporation of Delaware FFEQE Original application March 14, 1932, Serial No. 598,792. Divided and this application January 6, 1940, Serial No. 312,663

15 Claims. (Cl. 1136-1-47) This invention relates to furnaces provided trating a portion of the radiant heating section with radiant heating means and contemplates shown inFigure 3. f

the provision of heating apparatus constructed Figure. 6 iS a-oW diagram in Perspective illuS- with a plurality of combustion or re chambers trating a portion Of the radiant heating SeCtiOn in order to furnish a greatly increased area of shownin Figure 4. most effective heat absorbing surfaces. The Referring t0 Figure l, It indiCateS a furnaCe. major object of the invention is to provide a or refraetory Setting Which may @OnVeniently he. heating apparatus having a large area of most of boX or rectangular Shape. The furnace is effective heat absorbing surfaces. provided with bridge walls II and I 2, which sepa- An. equally important object of the invention rate the furnacevinto combustion or fire chamis to provide a heating apparatus in which several bers i 3 and I4 and a. Convection heating. SeCtion streams of oil may be heatedsimultaneously and I5- Burners are indicated at I5 and I7, irl the the temperature of each stream controlled by the lire Chamber i3, and at I3 in the re Chamber I4. provision of separate heating chambers therefor. A SCreerll Or baille Wall I9, WhiCh mayl be perfo.-

Another object of the invention is to provide a rated, is placed intermediate the burners I .6. heating apparatus constructed as a single furand Il. nace having an oil heating duty in excess of any One Stream Of Oil t0 be heated may he adi-,hing previousmitted through an inlet to a coil or tubular with these md other Objects in View, which section 2| located in the cooler section ofthe may be incident to the improvement, the inven- 20 Convection heating Zone I5. The oil passes fromV tion consists in the parts and combinations to be the Convectioncoil 2| to a coil comprising Wall hereinafter set forth and claimed, with the tubes 2.2, disposed about the walls of the re understanding that the several necessary elechamber I t. The coil 22 may well be disposed ments comprising the invention may be varied in about thefour walls of the chamber consisting construction, proportions and arrangement with- 25 0fy oner side of the. bridge Walls II and IZVand the out departing from the spirit and scope of the side walls-of the furnace. The heated oil passes appended @131mg from the coil 22 througha coil of roof tubes 23 The invention broadly contemplates a unitary adapted to receive radiant heat from the re furnace structure provided with a plurality of re Chamber Ill, the Oil being then diSCharged through chambers, each of which supplies radiant heat Outlet 24. l to elements arranged within the furnace, and The Other Straal-f1 0f Oil iS ShOWn aS heihgintrowith a common convection chamber into which duced toA an inlet Zito a convection heating coil the furnace'gases from the several fire chambers 26 positioned in thevhotter portion of the convecare directed. tion heating zonev l5. The oil passes thence The invention is particularly adapted for the through an intermediate radiant tube section 2l heating of hydrocarbon oils and in this connecdisposed kabout the baille IS. The Oil is then dition contemplates the provision of a maximum rectedthrough a rOW 0f lWall tubes 2 3 disposed amount of radiant heating surface adapted for 1h the Chamber I3 along the other sidev of the applying heat to the @1L bridge Wall I I and passes thence through oor I'n Order to make the invention more Cle-amy 40 tubes 29 to wall. tubes 3l! dlsposed adJacent one understood, there is shown in the accompanying 0f the Walls VIl! vof furnace. I'he oil then drawings, means for carrying the same into prac- DaSSeS through a radiant heating C011 3| disposed tical effect without limiting the improvements in about the four Walls of the re chamber lrcomtheir useful applications to the particularr con- Pfl-5mg the bridge Wall II and three Walls 0f the struction which, for the purpose of explanation, irlee IQ.v tlheulper oif thlel lfglde 1wall -D eour-a seco scage oa have been made the subnet of illustration, threewmu sentan 32, I through which the Oil In the drawings:

A passes to. radlant roof tubes 33 and out through Figure 1 1s a diagrammatic sectional elevation the outlet 34.

Gf a. partcutar embodiment o? the Invent-'lon 50 It is preferable to providein addition to the showing heatingmeans as applied to two sepaburners I6, n and wrcorresponding burners en mi? Streams of 011" tering. from the opposite wall to that from which @me 2 represents a dlagrammatlc' Sectlonal the burners I6, Il and I3 enter. It is to be unelevation of modified apparatus also shown as derstood however, that any number of burners adapted for heating two separate streams of oil. may be employed Without dpart-ling from the Figures 3 and i are left and Tight'hand VeWS scope of the invention. It is contemplated that respectively, in diagrammatic sectional elevation the games of the burners are projected inwardly of another modification shown as applied to the and that the combustion gases rise in combustion heating of a single stream of oil. chamber I3 to ow over the bridge wall II to be Figure 5 is a iiow diagram in perspective illus- -fsfl there contacted with the combustion gases rising in the combustion chamber I4, the combined gases then passing into the convection section to ow over the tubes in that section and finally passing to a iiue or chimney (not shown). Thus, all of the tubes disposed along the several surfaces, that is, the various wall tubes, floori tubes, roof tubes and the tubes adjacent the intermediate screen or baille I9 are heated substantially by radiant heat while the tubes located in the chamber I5 are heated by convection heat.

The heating apparatus of Figure 1 may be employed for various purposes, such for example, in the cracking of hydrocarbon oils, in which case both of the separate streams may be subjected to cracking temperatures, or if desired only one of the streams may be brought to a cracking temperature while the other stream may be more moderately heated. In one exemplification of the invention contemplated, one of the streams is employed as a high temperature cracking stream wherein considerable cracking may take place for the production of gasoline while the other stream may be subjected to a more moderate temperature. such for example, as may be applied to a crude for the purpose of enabling a moderate degree of cracking for the breaking or reducing of the viscosity of the oil. 'I'he discharge pipes 34 and 24 may be connected to suitable distilling apn paratus or to such reaction chambers as may be desired.

In the apparatus shown in Figure 2, a furnace Illa is provided with bridge walls IIa and I 2a to form fire chambers vection chamber |50,` supplied with burners at Ilia and I1a, while the re chamber I4a is supplied with burners Ilia. In one or more of the combustion chambers, such as is shown in the combustion chamber I3a. bafiles or screens Ilia, similar to the baille I9, are disposed intermediate the several burners. The baiiies or screens may conveniently be supported on pedestals 35.

The apparatus of Figure 2 is shown as applied to the heating of two separate streams of oil, one of which is heated entirely by radiant heat and the other of which is heated partly bv radiant heat and partly by convection heat. Thus, one stream may be introduced through an inlet 36 to a row of wall tubes 31 adiacent the bridge wall II thence to a section of floor tubes 38, thence to intermediate radiant tubes 39 disposed about the surfaces of one of the screens |901.. thence to another section of iioor tubes 4G, thence to another section of intermediate radiant tubes 4I disposed about the other screen Illa, thence to licor tubes 42 and thence to a row of side wall tubes 43 alone: one of the walls Illa.. The oil then passes through a section of four-wall tubes 44 disposed about the four walls of the combustion chamber I3a, including the bridge wall Ila. At the upper end of the bridge wall the four-wall tubes are changed to a three-wall section 45. from which the oil passes finally through roof tubes 4B to an outlet 41. Each section, other than the roof, of the several sections of coil .iust mentioned is shown as provided for dual flow, that is, each` section consists of pairs of pipes inter-connected so that the oil ows in two parallel streams through the several pairs of tubes of which each section is composed. If desired, however, the arrangement may be such that there is single flow entirely through all of the several coils. The stream thus introduced at the inlet petroleum or residuum thereof I3a and I4a and a conn The re chamber I3@ is 36 may be substantially entirely heated by radiant heat.

The other stream of oil enters through an inlet 48 through a coil section 49 positioned in a cooler section of the convection zone I5a, passes thence to a coil section 50 positioned in the hottest portion of the convection section I5a. I'he coil section 5B may advantageously, although not necessarily, consist of only a comparatively small section of coil, such as the two rows indicated, and may form a screening section through which relatively low temperature oil may be passed to thus protect the subsequent rows immediately underneath through which oil at a higher temperature may pass. The oil passes from the coil 5i) to wall tubes 5I disposed adjacent the bridge wall I2a, thence through floor tubes 52, thence through a row of wall tubes 53 adjacent the bridge wall I Ia, thence through a four-wall section of tubes 54 which are disposed about the walls of the combustion chamber I 4a, including the bridge walls IIa and I2a and the side walls of the furnace. The oil then passes through a section of roof tubes 55 and iinally through a coil section 56 disposed in an intermediate portion of the convection zone I5a and is iinally discharged through an outlet 51. The flow of oil of this second stream is also shown to be dual.

While the apparatus of Figure 2 may be employed for various purposes one advantageous application of this apparatus is in the carrying on of a combined crude reducing or a viscosity breaking operation with a cracking operation for the production of cracked gasoline. Thus, for example, a heavy crude or reduced crude, which it is desired to skim or strip or to crack to a comparatively slight extent, such as in a mere viscosity breaking operation, may be introduced Vthrough the inlet 48 and passed through the several sections of the coil positioned in the radiant heating zones of the lire chamber I4a. and in the convection zone I5a, the oil being then discharged through outlet 51 for distillation, while a cycle condensate obtained in the process may be passed to the inlet 3E and passed through the several sections of radiant heat coils disposed about the several walls of the re chamber I3a wherein the oil is cracked to the desired degree and may then be discharged through the pipe 41 into a reaction chamber for further cracking or passed directly to suitable distilling apparatus.

In Figures 3 and 4, a furnace or refractory setting Ille is provided with bridge walls Ilc and I2c to form combustion chambers I3c and I4c and a convection heating section I5c. The lire chamber I3c is supplied with burners at IBc and I1c and the iire chamber I4c is supplied with burners at ISC. Intermediate the several burners I6c and I1c in the fire chamber I3c are baliles or screens I!c, which may be suitably supported on pedestals 35e. Intermediate the several burners Ic in the lire chamber |40 are baiiies or screens 12, which may be suitably supported on pedestals 13.

The stream of oil to be treated in the apparatus of Figures 3 and 4 enters through an inlet line 14 to a section of coil 15 positioned in the convection heating zone I5c. The flow of oil through the coil 15 is indicated as being in quadruplet. The oil passes from the coil 15 through a connecting line 15' having branches 15, 11, 18 and 19. The oil in branch line 16 passes to a side wall section of tubes 8U in the combustion chamber I 4c adjacent the bridge wall I2c, thence through floor tubes BI., thence through tubes 82 disposed along the surfaces of one of the bailles 12, thence through an additionalv section of floor tubes k8f3 to a transfer line 84. The stream of oil entering the branch line .'l passes through wall tubes 85 in the re `chamber I'flc adjacent one side of the bridge Wall Ilc, thence through floor tubes 86, thence through a .section coil .8l disposed about the other `baille '3.2, 4thence through floor tubes 88 to a transfer line 89. The-oil entering the pipe 'I3 passes through Wall tubes 90 disposed along the other side of the bridge wall lic in the combustion chamber I3c, thence through floor tubes QI, thence through tubes 92 disposed along the surface of one of the intermediate screens ISc and thence through additional floor tubes 93 to a transfer line 94. The oil entering the other branch line 'I9 passes through wall tubes S adjacent one of the outer walls Iiic, thence through floor tubes 9S, thence through tubes 97 disposed along the surface of the other intermediate screen ISIC, thence through floor tubes 93 to transfer line 99.

The streams in the transfer lines 813 and 89 are merged in a line ISS for delivery to a fourwall coil section Iii! disposed about the Walls in the iire chamber itc, including the bridge walls IIc and I2C and the side Walls of the furnace, the oil flowing in dual flow through the coil I Il-l The oil then passes in dual flow through a three-Wall section |62 along the surfaces of the combustion chamber Mc, including the bridge Wall IIc and the side walls of the furnace. The oil then passes to a two-Wall section H13, one of the dual streams of oil from the coil IEIZ passing through one of the side wall coils H13 and the other stream passing through the other side Wall coil IBS, these side wall coils being located on opposite furnace Walls in the fire chamber Ille. The oil finally passes to roof tubes |04 in dual ovv and thence to an outlet pipe H55.

The streams of oil in the lines 94 and 99 are merged in the line iet by which they are conducted to a four-wall coil I'i disposed about the walls of the fire chamber IB'c, including three f Walls of the furnace and the bridge Wall IIc. The oil passes thence through a three-Wall section of coil Iii disposed about the three Walls of the furnace. Finally the oil passes through roof tubes 09 to outlet H8. The flow of oil through each of the coils I'l, Hi8 and |09 is shown in dual ovv.

The apparatus illustrated in Figures 3 to 6 is particularly adapted for the cracking of hydrocarbon oils, and it is contemplated that the oil at cracking temperature may be delivered through the transfer lines M35 and IID to a suitable reaction vessel or to a suitable distilling apparatus or both.

The baffles or screens positioned in the fire chambers for supporting additional heating coils, may be perforated if desired. By perfor-ating the baliles or screens, it is possible for the hot gases of combustion to pass through the sections of coil positioned adjacent the surfaces of the bailles or screens. By this expedient, additional heating of the oil passing through these sections of coil may be accomplished.

An important feature of the invention is the provision of unitary heating apparatus of maximumcapacity. This feature is particularly eX- emplied in the apparatus of'Figures 3 to 6 in which a furnace structure is provided of considerably greater capacity than has hitherto been possible.

It is contemplated that in the vapparatus sho-Wn, additional burners vmay be provided as on the opposite Walls from those in which the burners are placed. In the several structures shown in these several figures the various radiant heating tubes `located adjacent the interior surfaces of the lire chambers are preferably placed substantially out of the path of the convection gases so that they may not be subjected to direct convection heat in the fire chambers and are lheated by the radiant heat afforded by the several burners in the fire chambers. Itis contemplated that the 'furnace gases after being passed from the fire chambers to one of the convection zones and after flowing over the elements to be heated therein may be passed to a suitable flue or chimney, not shown. In one method of operation contemplated by the invention, the convection heating section may be eliminated and the furnace gases Which are discharged from the re chambers may be employed in preheating the air supply to the burners.

The separate control of the degree of radiant heat applied in the several radiant heating zones provided by the invention is an advantageous feature thereof, particularly in the case of cracking operations. Thus, the oil stream passing through the furnace may be rapidly raised to a cracking temperature and the soaking heat required in the final sections of the coil may be very accurately controlled in accordance 'with my invention.

An important method of operation contemplated by the invention is to heat separate streams of oil which may have different characteristics requiring different degrees of heat` for cracking in separately controlled radiant heating sections. Thus for example, in the apparatus of Figure 1, one stream of oil after preferably being preheated in the convection coil 26 may be passed through the radiant conduits positioned in the i-lre chamber I3 while another stream of oil after being preferably preheated in the convection coil 2i may be passed through the radiant heating conduits of the fire chamber lli, the re chambers I3 and i4 being separately controlled so that the desired cracking temperature may be applied in each instance. The two separate streams of oil may be derived from various sources, thus, one stream may be raw charging stock while the other may be cycle condensate obtained in the process or both streams may be withdrawn from the fractionating zone of the system but removed. from dierent points therein. In the apparatus of Figures 3 and 4, for example, two cuts may be Withdrawn from the fractionating Zone, one cut b'eing passed through the radiant heating conduits of the fire chamber I3c While the other stream may be passed through the radiant heating conduits of the fire chamber Ic or if desired a greater number of cuts of varying boiling points may be Withdrawn from the fractionating zone and passed through separately controlled radiant heating zones of the furnace.

It is to be understood that this invention comprehends that the tubes may functionto shield a part or all of the interior surfaces of the furnace adjacent which they are positioned to such an extent that they will radiate little or no heat, although if desired, the arrangement maybe such that the Walls may function as heat radiating or reflecting surfaces. v

While there is shown and described the preferred embodiments of the invention and specic examples of operation for each, it is to be clearly understood that the invention is not to be limited by the precise details of construction herein set forth, by way of illustration, as it is apparent that many changes and variations may be made therein, by those skilled in the art, without departing from the spirit of the invention, or exceeding the scope of the appended claims.

This case is filed as a division on my application Serial No. 598,792, filed March 14, 1932, for Heating apparatus.

I claim:

1. A heating apparatus of the character described comprising a furnace provided with a plurality of bridge walls arranged to form a plurality of fire chambers and a convection chamber disposed to receive furnace gases owing over the bridge walls from the fire chambers, a plurality of burners in each of said fire chambers, a screen disposed between burners in at least one of said fire chambers and heat absorbing elements disposed along the surfaces of said screen and along the walls of the re chambers.

2. In a furnace having walls forming a combustion and radiant heating zone, the combination of fluid heating means, comprising a vertical row of horizontal tubes, centrally disposed in said zone, a horizontal row of serially connected, horizontal tubes in the lower portion of said zone beneath said fluid heating means, a second horizontal row of serially connected, horizontal tubes in the upper portion of said zone above said uid heating means, and means for supplying fuel to said zone on opposite sides of said fluid heating means.

3. In a furnace having a pair of spaced vertical walls, a roof and a floor, the combination of a vertical row of horizontal tubes between and spaced from said Walls, a horizontal row of serially connected, horizontal tubes adjacent the roof above said vertical row of tubes, a horizontal row of serially connected, horizontal tubes adjacent the floor beneath said vertical row of tubes, and means for burning fuel in the space between said vertical row and each of said walls.

4. A furnace comprising walls forming a pair of combustion zones and a convection heating zone, heating tubes in the convection zone and means for passing combustion gases from both said combustion zones through the convection zone, a vertical row of horizontal heating tubes in each of the combustion zones, means for firing each of the combustion zones on opposite sides of the vertical row of tubes therein, a horizontal row of heating tubes in the lower portion of each of the combustion zones below the vertical row of tubes therein, and a horizontal row of tubes in the upper portion of the furnace and having tubes disposed in each of the combustion zones.

5. In a furnace for heating hydrocarbon oils comprising a main furnace structure having side walls, end walls, a roof and a floor, the combination with vertical partition walls between said sides of the main furnace structure dividing the same into a plurality of separate combustion and heating zones, means for independently supplying combustibles to each combustion zone, means for removing combustion gases from each combustion zone and passing the same through a convection heating zone, a fluid conduit located within said convection heating zone and supplied with available convection heat from said combustion gases, a communicating fluid conduit located adjacent the floor of the furnace directly beneath said combustion zones and comprising horizontally disposed tubes heated by direct radiation from the combustion gases, another communicating uid conduit between and spaced from said side walls comprising a vertical row of horizontal tubes in each combustion and heating zone, and means for subjecting said uid conduit in said heating and combustion zones to direct radiation from flames.

6. In a furnace for heating hydrocarbon oils comprising a main furnace structure having side walls, end walls, a roof and a oor, the combination with vertical partition Walls between said sides of the main furnace structure dividing the same into a plurality of separate combustion and heating zones, means for independently supplying combustibles to each combustion zone, means for removing combustion gases from each combustion zone and passing the same through a convection heating zone, a fluid conduit located within said convection heating zone and supplied with available convection heat from said combustion gases, a communicating uid conduit located adjacent the floor of the furnace directly beneath said combustion zones and comprising horizontally disposed tubes heated by direct radiation from the combustion gases, another communicating fluid conduit between and spaced from said side walls comprising a pair of parallel vertical rows of horizontal tubes in each combustion and heating zone, and means for subjecting said fluid conduit in said heating and combustion zones to direct radiation from flames.

'1. A furnace comprising walls forming a pair of combustion zones and a convection heating zone, heating tubes in the convection zone and means for passing combustion gases from both said combustion zones through the convection zone, a vertical row of horizontal heating tubes in each of the combustion zones, means for ring each of the combustion zones on opposite sides of the vertical row of tubes therein, and a horizontal row of heating tubes in the lower portion of each of the combustion zones below the vertical row of tubes therein.

8. In a furnace having a combustion zone and a convection zone adapted to receive combustion gases from the combustion zone, the combination of a plurality of banks of heating tubes so arranged in the convection zone as to be substantially uniformly heated by said gases, a row of serially connected oor tubes and a row of serially connected roof tubes in the combustion zone, means for passing uid to be heated in a plurality of parallel streams through the banks of tubes in the convection zone, and means for passing a portion of the fluid heated in said convection zone through said floor tubes and for passing another portion of the fluid heated in said convection zone through said roof tubes.

9. In a furnace having at least two combustion zones and a convection zone adapted to receive combustion gases therefrom, the combination of a plurality of banks of heating tubes so arranged in the convection zone as to be substantially uniformly heated by said gases, a row of serially connected floor tubes in one of said combustion zones and a row of serially connected roof tubes in another of said combustion zones, means for passing fluid to be heated in a plurality of parallel streams through the banks of tubes in the convection zone, and means for passing a portion of the fluid heated in said convection zone through said floor tubes and for passing another portion of the uid heated in said convection zone through said roof tubes.

10. A furnace for the heating of fluids which comprises, in combination, two separate combustion and heating zones, rri'eans for independently supplying hot combustion products in regulated amounts to each combustion and heating zone, a convection heating zone forming part of said furnace and associated with said separate combustion land heating zones, means for passing combustion gases from each combustion and heating zone through said convection heating zone, a uid conduit located adjacent the roof of each combustion and heating zone, a fluid conduit located adjacent the oor of each combustion and heating zone, a uid conduit located within the convection heating zone, means for passing hydrocarbon oil in a continuous stream through the fluid conduit adjacent the floor of one combustion and heating zone and then through the fluid conduit adjacent the roof of the same zone, means for simultaneously passing a different hydrocarbon oil in a continuous stream through the fluid conduit in the convection heating zone, then through the fluid conduit adjacent the oor of the other combustion and heating zone and then through the fluid conduit adjacent the roof of the last mentioned combustion and heating zone.

11. In the heating of hydrocarbon fluids to conversion temperature in furnaces of the character having a pair of independently red combustion zones and Ia convection zone supplied with combustion gases from both of said combustion zones, the method which comprises passing a hydrocarbon oil in a continuous uninterrupted stream through one of said combustion zones adjacent the floor and adjacent the roof thereof, simultaneously passing a second hydrocarbon oil in a continuous uninterrupted stream through the convection zone and through the other of said combustion zones adjacent the oor and adjacent the roof thereof, the streams being subjected to strong heating while adjacent the floor of each combustion zone.

12. A method of heating hydrocarbon fluids to conversion temperature in a furnace having a bridge wall and a combustion chamber which comprises passing hydrocarbon fluid through spaced vertical banks of tubes arranged in said combustion chamber to subdivide it into a plurality of heating sections, separately supplying hot products of combustion to each heating section to direct products of combustion between said banks of tubes in each heating section, subjecting the tubes to heat radiated directly from hot products of combustion supplied to each heating section to thereby apply radiant heat to exposed sides of each of said tubes in intermediate banks of tubes, passing at least part of the hydrocarbon uid first through a bank of tubes adjacent the wall opposite said bridge wall and thence through an intermediate bank of tubes and commingling the hot products of combustion leaving said heating sections and withdrawing the commingled hot products of cornbustion through a common outlet adjacent said bridge wall.

13. In a furnace for heating hydrocarbon oils comprising a main furnace structure having side walls, end walls, a roof and a floor, the combination with partition walls extending between said sides from near the oor towards the roof CII of the main furnace structure dividing the same into a plurality of separate combustion and heating zones, means for independently supplying combustibles to each combustion zone, means for removing combustion gases from each combustion zone and passing the same through a convection heating zone, a fluid conduit located within said convection heating zone and supplied with available convection heat from said combustion gases, a communicating fluid conduit located adjacent the floor of the furnace directly beneath said combustion zones and comprising horizontally disposed tubes heated by direct radiation from the combustion gases, another communicating iluid conduit between and spaced from said side walls comprising a pair of parallel vertical rows of horizontal tubes in each combustion and heating zone, and means for subjecting said fluid conduit in said heating and combustion zones to direct radiation from flames.

14. In a furnace for heating hydrocarbon oils comprising a main furnace structure having side walls, end walls, a roof and a floor, the combination with vertical partition walls between said sides of the main furnace structure dividing the same into a plurality of separate combustion and heating zones, means for independently supplying combustibles to each combustion zone, means for removing combustion gases from each combustion zone and passing the same through a convection heating zone, a fluid conduit located within said convection heating zone and supplied with available convection heat from said combustion gases, a communicating uid conduit located adjacent the floor of the furnace directly beneath said combustion zones and comprising horizontally disposed tubes heated on one side by direct radiation from' the combustion gases and on the opposite side by reilected radiation from the floor, another communicating fluid conduit comprising a vertical row of horizontal tubes in each combustion and heating zone and means for subjecting opposite sides of said last-mentioned fluid conduit in said heating and combustion zones to direct radiation from flames.

15. In a furnace for heating hydrocarbon oils comprising a main furnace structure having side walls, end walls, a roof and a floor, the combination with vertical partition walls between said sides of the main furnace structure dividing the same into a plurality of separate combustion and heating zones, means for independently supplying combustibles to each combustion zone, means for removing combustion gases from each combustion zone and passing the same through a convection heating zone, a uid conduit located witln'n said convection heating zone and supplied with available convection heat from said combustion gases, a communicating uid conduit located adjacent the floor of the furnace directly beneath said combustion zones and comprising horizontally disposed tubes heated on one side -by direct radiation from the combustion gases and on the opposite side by reflected radiation from the oor, another communicating fluid conduit comprising a pair of parallel Vertical rows of horizontal tubes in each combustion and heating zone, and means for subjecting said lastmentioned fluid conduit in said heating and combustion zones to direct radiation from flames.

DUS'IIN W. WILSON. 

